cat 303.5 turbo VNT adjustment

[scottwolowich]

Hey there, I have a new to me 2006 cat 303.5c serial dmy00326 and it has the mitsubishi s3q2-t turbo diesel engine in it. I've been going over the whole machine and getting it up to snuff and it's been a bit of an adventure. I noticed that the vane lever on the turbo was pretty sticky and the actuator rod seems out of adjustment. I had a volkswagen TDI car with a VNT (vacuum actuated) turbo and I had instructions on adjusting it based on how much the lever should travel based on a certain vacuum pressure. I can't find any literature on the mitsubishi engine or td03 turbo. I'll probably attempt to wing it to get it to operate at max pull/vane opening at full throttle but I was wondering if anyone had experience adjusting this specific turbo/engine vane control? Thanks!

 

[scottwolowich]

actually it must be a wastegate!

 

[scottwolowich]

okay it seems as though the wastegate actuator is adjusted so that it runs at full boost (closed) the entire time. is this the intended design? any input is appreciated. the engine only runs at basically idle or full throttle so i imagine this adjustment doesn't matter much.

 

[Nige]

okay it seems as though the wastegate actuator is adjusted so that it runs at full boost (closed) the entire time. is this the intended design? any input is appreciated. the engine only runs at basically idle or full throttle so i imagine this adjustment doesn't matter much.

The boost setup is designed so that the turbo gives higher boost pressures at lower RPM. The wastegate is only set to blow off if boost pressure reaches "max allowable". 99.99% of the time the wastegate will be closed. See diagram below, it might explain it better. The orange line is boost with a wastegate, the red line the boost that would be achieved without a wastegate - much higher boost at lower engine RPM where you need it.

 

[scottwolowich]

So the wastegate actuator plunger is pressure activated and when it reaches the max pressure then it pushes the plunger rod out and opens the wastegate. That would make sense.

I was investigating it as I have been looking into a minor issue on my machine. Now that I fixed the wiring on the starter it starts fine and reliably every time except it takes the engine maybe 10s to fully get going, almost like it's running lean or rich or only on 2/3 cylinders for 10 seconds and then it fires up fine. I was wondering if it was taking a bit of time to build boost pressure so I was investigating the system. I should look into the glow plug system as well to make sure all is functioning there as well. Thank you for the reply.

 

[Nige]

At the speeds the starter will crank the engine there will be no boost pressure. Take a look at the glow plugs next would be a good idea, especially if ambient temperatures are a bit on the low side.
If you want an Electrical Schematic start a conversation with me (click on my username to the left) and give me the Serial Number plus your email address.

 

[scottwolowich]

I understand, it's more after I stop cranking and the engine is running but not fully, it takes a little while to start firing evenly and at proper speed/sound, maybe 10-15 seconds. I'll look into the glow plugs.

 

[thepumpguysc]

Yes glow plugs are necessary for quick starting.. also check to make sure the fuel is there..
IF u have a bleed-back problem, it will take longer for the fuel to pump up to the inj. pump inorder for it to start injecting fuel to start.. but once the fuel is "up there" its fine until u shut it off again.. then the cycle starts all over again..
IF it has a hand primer somewhere in the system.?? Just for kicks & giggles, pump the hand primer 10-15-20 times BEFORE u TRY TO start it .. & see if it fires off any quicker..
IF IT DOES, u gotta bleed-back issue..
Good luck.. & check that GP system.. meaning power TO & actual glowing plugs.. {not hard}

 

[scottwolowich]

Yes glow plugs are necessary for quick starting.. also check to make sure the fuel is there..
IF u have a bleed-back problem, it will take longer for the fuel to pump up to the inj. pump inorder for it to start injecting fuel to start.. but once the fuel is "up there" its fine until u shut it off again.. then the cycle starts all over again..
IF it has a hand primer somewhere in the system.?? Just for kicks & giggles, pump the hand primer 10-15-20 times BEFORE u TRY TO start it .. & see if it fires off any quicker..
IF IT DOES, u gotta bleed-back issue..
Good luck.. & check that GP system.. meaning power TO & actual glowing plugs.. {not hard}

Checked resistance on individual glow plugs and all zero. Got 12v to the harness for 6 seconds in 20 degree celsius weather (68F). I'm going to look into the fuel system now. It seemed to start a bit better today (started good, fire unevenly for under 10 seconds, and then proper firing). I did fiddle with the fuel separator a bit it didn't seem to be in quite perfectly so that could do it.

 

[thepumpguysc]

CYCLE the key switch 2-3 x to get the GP's to activate longer.. & see what that does.

 

[scottwolowich]

I was having issues with my fuel shutoff. It is a cable that is pulled using a lever similar to a brake cable lever on a bicycle. It was very difficult to shut off and seemed to have been jerry rigged using a spare bolt. Anyways it finally broke and in the process of troubleshooting I found that the return spring was not pulling the shut off cable all of the way back. So the reason for hard starting was because the fuel shutoff cable was sometimes partially pulled. If I reset the cable by hand before starting the machine it starts like a dream on the first revolution. Now time to fix up this fuel shutoff cable mechanism that is in the depths of the machine.